The first Paleo-Indians (AKA Paleo-Americans) are believed to have reached the western hemisphere around 14,000 years ago by crossing Beringia, the landmass then connecting Asia to Alaska. (A recent, though controversial analysis, suggests humans reached North America earlier by crossing the north Atlantic ice.)

Now, new findings at an ice age fossil site near Snowmass Village, Colorado hint at possible human migration to North America many thousands of years earlier. Following the sites discovery by a construction worker in October 2010, researchers have recovered 4,800 fossils including a Columbian mammoth. Interestingly, the most curious findings were “soccer ball-sized stones.” According to aspendailynewsonline:

The possible presence of Paleo-Indians arose when Drs. Kirk Johnson and Ian Miller, co-leaders of the dig, and others noticed small boulders where they shouldn’t have been. Several soccer ball-sized stones were found in what was once the middle of the ancient lake. The rocks were next to, above and below a partial mammoth skeleton, Johnson said Wednesday.

The stones may be evidence of mammoth hunting by Paleolithic humans. However, there is one problem: as far as we know, humankind was not in the western hemisphere at that time! The ice-age fossils are “estimated to be between 40,000 and 150,000 years old.” This would put humans in North America 26,000 years earlier than current evidence indicates.

Currently at the Denver Museum of Nature & Science, the animal fossils will be studied extensively including searching for marks that would indicate butchering by humans. If they are found, it will dramatically rewrite the history of human migration during the Middle Paleolithic.